Simplify the Expression $\left( 5 ^ { 3 } \right) ^ { 3 }$

Multiple Choice

Simplify the expression. Assume all variables represent nonzero real numbers.
- $\left( 5 ^ { 3 } \right) ^ { 3 }$

A) $5^{6}$
B) $25 ^ { 9 }$
C) $5 ^ { 9 }$
D) $25^{6}$